A conventional electrostatic actuator includes a stator provided with electrodes and a movable element having a resistance element such as a film. For such an electrostatic actuator, a driving method is used with multiphase signals.
Unfortunately, in such an electrostatic actuator, a movable element linearly moving on a stator may meander or laterally deviate due to in-plane variations in friction resistance or foreign matters.
To address this problem, a conventional electrostatic actuator is provided with a guide that prevents meandering and a lateral deviation of a movable element. However, a friction resistance between the guide and the movable element may interfere with a movement of the movable element, and friction between the guide and the movable element may cause an unnecessary electric charge. Moreover, the movable element is regulated by the position of the guide but a restoring force to the center is not applied to the movable element.
Thus, a conventional electrostatic actuator has voltage supply lines on both sides of electrodes along the direction of movement of a movable element (for example, JP03-65081). With this configuration, a moment component perpendicular to the direction of movement of the movable element is fixed by the electrostatic force of the two voltage supply lines on both sides of the electrodes. Thus, the occurrence of a rotation moment on the movable element is suppressed, preventing meandering of the movable element.
In the conventional electrostatic actuator; unfortunately, the movable element is attracted to the voltage supply lines by the electrostatic force of the voltage supply lines, increasing the friction resistance of the movable element. Since the electrostatic force of the voltage supply lines does not contain a moment component that restores the movable element to the center of a stator, a restoring force to the center of the stator is not applied to the movable element and the movable element keeps moving while being deviated from the center of the stator.